Brief Announcement: Not a COINcidence: Sub-Quadratic Asynchronous Byzantine Agreement WHP

Cohen, Shir; Keidar, Idit; Spiegelman, Alexander

doi:10.1145/3382734.3405708

Cited by 13 publications

(21 citation statements)

References 14 publications

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“…In some cases, randomized BA requires deterministic validity and agreement while allowing termination with probability 1. Other works [16,21,24] solve BA with high probability, where all properties are assured with high probability.…”

Section: Models and Definitionsmentioning

confidence: 99%

“…A few recent studies have used randomness to circumvent Dolev and Reischuk's lower bound and provide BA solutions with sub-quadratic word complexity [2,6,16,21,24,26,32,33,37] in all three models. There are two approaches to using probability.…”

Section: Introductionmentioning

confidence: 99%

“…The first is weakening the problem guarantees to probabilistic ones. Works in this vein usually utilize committee sampling, assume an adaptive adversary, and provide probabilistic safety and liveness [16,21,24,32]. The second considers models in which deterministic BA solutions are possible, and designs protocols where the expected complexity is sub-quadratic [2,6,26,33,37].…”

Section: Introductionmentioning

confidence: 99%

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Byzantine Agreement with Less Communication

2021

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The development of reliable distributed systems often relies on Byzantine Agreement (BA) [26]. In this problem, a set of correct processes aim to reach a common decision, despite the presence of malicious ones. BA has been around for four decades, yet practical use-cases for it in large-scale systems have emerged only in the last decade. One major application for BA is cryptocurrencies. For example, Bitcoin [30], the rst cryptocurrency, requires a large set of users to agree on the state of the blockchain. Since Bitcoin is a real currency with real value, the need to protect it against Byzantine users is crucial. Following Bitcoin, many other blockchains and FinTech platforms have emerged, e.g., [6,21,30,36]. Consequently, an efficient implementation, in terms of communication, has become one of the main foci of BA solutions.

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Section: Models and Definitionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Byzantine Agreement with Less Communication

2021

Self Cite

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“…Static corruptions are done before the protocol begins but can be a function of the trusted setup; adaptive corruptions can occur during the course of the protocol. ( †) The protocols from [1,8,22,26] reach agreement from scratch (hence also from almost-everywhere agreement) with amortized˜(1) communication per party; the expected round complexity is constant and termination is guaranteed in polylog( ) rounds.…”

Section: Technical Overviewmentioning

confidence: 99%

“…Without this extra model assumption, their VRF approach does not apply. We note that several recent consensus protocols [1,8,18,19,25,26,58,59] also follow the sortition approach of [22]; however, similar to our first construction, their PKI is assumed to be honestly generated by a trusted third party. Theorem 2.7 (SRDS from OWF and trusted PKI, informal).…”

Section: Srds Constructionsmentioning

confidence: 99%

Breaking the O(√ n)-Bit Barrier

Boyle

Cohen

Goel

2021

Proceedings of the 2021 ACM Symposium on Principles of Distributed Computing

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Byzantine agreement (BA), the task of parties to agree on one of their input bits in the face of malicious agents, is a powerful primitive that lies at the core of a vast range of distributed protocols. Interestingly, in BA protocols with the best overall communication, the demands of the parties are highly unbalanced: the amortized cost is˜(1) bits per party, but some parties must send Ω( ) bits. In best known balanced protocols, the overall communication is sub-optimal, with each party communicating˜( √). In this work, we ask whether asymmetry is inherent for optimizing total communication. In particular, is BA possible where each party communicates only˜(1) bits? Our contributions in this line are as follows:• We define a cryptographic primitive-succinctly reconstructed distributed signatures (SRDS)-that suffices for constructing˜(1) balanced BA. We provide two constructions of SRDS from different cryptographic and Public-Key Infrastructure (PKI) assumptions. • The SRDS-based BA follows a paradigm of boosting from "almosteverywhere" agreement to full agreement, and does so in a single round. Complementarily, we prove that PKI setup and cryptographic assumptions are necessary for such protocols in which every party sends ( ) messages. • We further explore connections between a natural approach toward attaining SRDS and average-case succinct non-interactive argument systems (SNARGs) for a particular type of NP-Complete problems (generalizing Subset-Sum and Subset-Product). Our results provide new approaches forward, as well as limitations and barriers, towards minimizing per-party communication of BA. In particular, we construct the first two BA protocols with(1) balanced communication, offering a tradeoff between setup and cryptographic assumptions, and answering an open question presented by King and Saia (DISC'09).

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